<![CDATA[<B>Sequential histomorphometric study of the left internal thoracic artery</B>]]>

Abstract

Objective: The use of left internal thoracic artery (LITA) in coronary artery bypass surgery is currently recognized as the best option, providing lower incidences of cardiovascular events and superior long-term survival. Now, incremental utilization of these grafts makes a reassessment of its histological structure necessary. Therefore, the purpose of this study was to examine and compare the sequential histological structure of LITA.Method: Specimens of LITA harvested from 18 cadavers, divided into nine proportional segments, were studied. Cuts of each segment were stained by the Verhoeff-Van Gieson technique. The following parameters were analyzed: perimeter of the arterial lumen, thickness of the intima, thickness of the media layer, amount of elastic fiber in the media layer and the elastic fiber density.Results: The collected data showed that perimeter of the LITA decreases downstream on its course, the thickness of the intima is increased in the proximal segments, the thickness of the media layer diminishes throughout its extension, the number of elastic fibers is concentrated in the intermediate segments and the density of elastic fibers is reduced in the proximal and distal segments. Conclusion:Therefore, the findings of the present study validate the heterogeneity of the LITA sequential histological structure. Descriptors

Histomorphometric and sympathetic innervation of the human internal thoracic artery

“…The results of this study show that intimal thickening or atherosclerosis was not seen in the ITA, though discontinuations are seen in ITA samples above 60 years of age. This may be because the ITA has natural immunity to atherosclerosis, active vasodilatation is accompanied by remodeling of the arterial wall, it has a great capacity for nitric oxide secretion and other endothelial factors, regulating the vasomotor tonus and the auto‐repair mechanism 18. Reports of Sandow et al have suggested that internal elastic lamina hole density is not related to hypertension or intimal lesion formation in rats 19.…”

Conduits Used in Coronary Artery Bypass Grafting: A Review of Morphological Studies

“…2,39) Currently, it is considered the standard for CABG and is recognized by cardiothoracic surgeons as the most effective and reliable conduit due to its excellent permeability, lower incidence of adverse events, and greater long-term survival for the patient. 2,4,5,8,29,[40][41][42] The higher permeability of this conduit is attributed to the morphological characteristics of the wall, 5,[40][41][42][43] as its histological structure makes it relatively free of atherosclerosis as well as from intimal hyperplasia. 29,[40][41][42][43][44] Both left and right ITAs can be used either in situ or as a free graft.…”

“…2,4,5,8,29,[40][41][42] The higher permeability of this conduit is attributed to the morphological characteristics of the wall, 5,[40][41][42][43] as its histological structure makes it relatively free of atherosclerosis as well as from intimal hyperplasia. 29,[40][41][42][43][44] Both left and right ITAs can be used either in situ or as a free graft. 5,29) The left ITA is used more often than the right because of its location and proximity to the heart, allowing for a better anastomosis.…”

“…5) Morphological studies report that the ITA does not present a uniform structure along its length, and is known as a transitional artery. [40][41][42][43] This may have implications regarding its use and thus interfere with the results of CABG, 44) and this is the reason why the morphology of specific segments is important. There are studies that evidence differences between the left and right ITA, 42) as well as they report similarities in their structure.…”

“…43) The permeability of the ITA is superior to that of all other conduits used in CABG. 2,5,28,[40][41][42] The left ITA, when anastomosed with the AIA, has a permeability of 99% at 5 years, 97% at 10 years, 90%-95% at 15 years, and 90% at 20 years. 2,4,5,28) When anastomosed with the CX, its permeability is 97% at 5 years, 92% at 8 years, 89% at 10 years, 4) and 91% at 15 years.…”